World's Finest Returns
by DfangOO
Summary: Kara will never forget her meeting with Barry Allen, the Flash from another earth. Now she is about to meet the Flash of her earth.
1. Chapter 1

**Disclaimer: I do not own Supergirl or the Flash or anything related. This is a fan created story for entertainment and no profit will be made.**

 **Note: For the Flash's suit imagine the suit from the show with the white emblem, but brighter red with yellow boots and belt.**

 **This story takes place after the first episode of season 2.**

 **Chapter 1**

It was a seemingly calm night in Central City. A Star Labs security guard is eating Big Belly Burger and listening to the football game while keeping an eye on the cameras. Outside a figure was approaching the door concealing a gun. The security guard noticed this and went to the front door to investigate. This proved to be his last mistake as when he was tricked into opening the door he was frozen in ice.

The figure made his way through the lab until he reached a vault. After freezing and breaking it open he found what he was after, a green glowing piece of meteor rock.

Barry Allen, CSI for the CCPD walked in looking around at the damage. His eyes quickly landed on the dead body before looking over at one the employees at Star Labs. Tina McGee, Barry's friend, doctor and the only one to know his secret. Not long ago Barry had an accident in his lab that resulted in him being changed in extraordinary ways. It has only been a month, but he has been secretly helping people as a masked hero known as the Flash.

"Tina, are you alright?"

"I'm fine Barry. I wasn't even here," she assured him.

"Barry, what took you so long," one of the detectives was approaching him. It was Detective Joe West, the father of his childhood friend Iris. He was also friends with his dad who was eliminated as a suspect in her murder due to being at work when it happened.

"Sorry Joe. I uh, got held up by traffic. It looks like it was Snart again."

"Yeah, but it doesn't make any sense. Snart usually goes for banks, paintings. So what could he want at Star Labs?"

"I can answer that detective," said Tina. "He stole a green meteor rock. It's called Kryptonite and it was sent to us to study."

"As in Superman and Krypton?" Barry was looking astonished. "You mean this is related to Superman. Something like that has been here?"

"Why would Snart be interested in something like that?" Joe took a sip of his coffee. One of the other officers at the scene commented that the Flash catch Snart. "Come on Bellows, not that again. The Flash is a myth."

Later that day at CCPD Barry was working in the crime lab. His friend and Co-worker Julio Mendez were working on another case when Tina walked in. "Hey Barry. Has there been any news?"

"I haven't heard anything yet. We'll get it back Tina."

"I know, it's just that. Some people who said they work for the government came to me with the rock in the first place. When they here about it being stolen they aren't going to be happy. I want to help, this could cost me my job and who knows what else if I don't get it back."

"Bary," Joe said as he walked in. "Snart left town for National City last night. Captain Singh wants us over there."

"National City? Where Supergirl lives?"

"Detective West, I want to come too. My job and possible future depends on getting that Kryptonite back. It was supposed to remain top secret, I can help and I won't get in your way."

"Joe, this is obviously very important to Tina. It couldn't hurt to let her tag along right?"

"Fine, but as long you don't get in our way and let us do our job."

In National City Kara Danvers was starting her first day as a reporter. After working as an assistant to Cat Grant she was heading into new territory. She was anxious but her cousin Clark was there to give her support.

She was walking into her apartment that she shared with her sister Alex to find Clark working on his laptop. She assumed he must be working on a story. "Hey Kara, how'd it go?"

"Well I got my first story, an old theater that' s about to be torn down." Clark commented that she didn't seem too exited about it. "I guess I was just hoping for something bigger."

"Kara, you're just starting out. You'll get there, you just need to work your way up and prove yourself."

"I know, you're right." Kara sighed and kicked off her shoes. "So what are you working on? A story?"

"Yeah, Lois called and told me about a criminal from Central City that arrived here in National City. She asked me to look into it. She would normally want to do this herself, but she's working on something else."

Kara had stopped paying attention at a certain point. The mention of Central City made something click in her mind. She still remembered meeting a superhero from another Earth. Barry Allen had somehow ended up on her Earth and needed her help to get home. While he was here he helped her stop Livewire and Banshee.

"Did you say Central City? Who is this criminal?"

"Leonard Snart, goes by Captain Cold because he uses a freezing gun. Why?"

Kara then told him about meeting the Flash from another Earth. He was from Central City and they both helped each other. In the short time he had been here she had come to consider him a friend.

"Parallel Earths, I've never been to one myself. To travel so fast that you punch a whole in the dimensional barrier, that's impressive. Sounds like a nice guy."

Kara couldn't help but smile. "Yeah, did you know he actually wanted to get his picture taken with my spaceship? He was so excited about the whole alien thing."

That night Snart was waiting in an alley. It wasn't long before a limo pulled up with tinted windows. The window in back rolled down and he walked up to it. "I got your rock." He handed the Kryptonite to the figure inside in exchange for payment.

"And the police from Central City. They're here looking for you."

"The deal was for me to bring you the rock. "

"I don't want them interfering. Take care of them, and you will be paid double." Snart agreed and the meeting was soon ended as the limo drove away.

Joe walked into National City's police department with Barry and Tina. They were shown to the captain's office who was expecting them. "You must be the people from CCPD. Your captain called and requested we work together to catch Snart."

"What's he doing in my city?"

"That, is what we are here to find out. He stole something from Star Labs and may have brought it here." Joe said. "His cold gun is very dangerous. You and your men need to be careful with him."

Unbeknownst to them someone could hear everything they were saying. Clark was there to get more information on Snart and his whereabouts. As they walked out of the captain's office Joe and Tina went outside ahead of Barry as he stopped for a drink. Clark saw this as his chance to approach him and get more information.

"Excuse me." Barry turned to see the stranger with glasses coming toward him. "Clark Kent, Daily Planet. I'm writing a story on Leonard Snart, he was seen exiting a plane here in National City. The lady at the desk told me you were CCPD, so he's one your's correct?"

"Daily Planet, you guys have close ties to Superman right?"

"Well, Superman has given us a fair number of exclusives. I believe we were talking about Captain Cold though."

"No this is related, if you needed to get a message to Superman could you?"

"I could find a way, what's this about?"

"Look," Barry sighed and ran his hands over his face. "I don't know if I should be telling you this. I've read your articles Mr. Kent and I know your reputation. If I tell you this can I trust you to keep it between us and only tell Superman and Supergirl? My friend's job is on the line right now and none of this is her fault."

When Clark assured him it would stay between them Barry continued, "Snart stole something from Star Labs related to Superman and Supergirl. Ever heard of Kryptonite?"

Clark suddenly got a sinking feeling in his stomach. This is what he had feared, Kryptonite ending up in the wrong hands. "Rings a bell."

"I don't know what this stuff is or what it does, but if it's related to Superman and Supergirl they would want to know about it."

"Thank you for telling me this. I'll make sure that they both hear of this. How did Star Labs get ahold of Kryptonite in the first place?"

"My friend said some government guys sent it to her for study. She couldn't have known something like this would happen, much less prevented it. Snart is smart and with that cold gun he's dangerous."

"Thank you for trusting me with this. What was your name?"

"I'm Barry, Barry Allen. I'm a CSI for the CCPD." Barry shook Clarks' hand who suddenly went wide eyed. Kara had just told him of the Barry from another earth, so this must be the one from their's. Was he also the Flash here Clark wondered.

"Barry," Joe called from the front door. "What's taking so long?"

"Sorry Joe, It was nice meeting you Mr. Kent."

"Nice meeting you." Clark watched as they left. He guessed time would tell if Barry was the Flash or not. His mind soon turned to another matter. How unhappy he was that a piece of Kryptonite had ended up at Star Labs and he didn't know about it.


	2. Chapter 2

**Disclaimer: I do not own Supergirl or the Flash or anything related. This is a fan created story for entertainment and no profit will be made.**

 **Note: Okay I think I need to clarify something to clear up any confusion. I really should have done this last chapter, but this is Grant Gustin's Flash. John Wesley Shipp is still Barry's dad. I'm just merging the two Flash shows together. I don't know how obvious it is but I thought I'd clear up any confusion.**

 **So this is Grant Gustin's Flash. The Reverse Flash still killed his mom. His dad didn't go to jail for the murder. He was at work when it happened and was eliminated as a suspect. Barry and Julio work together and are friends. The Particle Accelerator still went off, but Barry was never in a coma. He went to Tina after discovering his powers (just like in the 90s Flash) and she has been helping him as the Flash. Barry still grew up with Iris, who is dating Eddie like in the first season.**

 **I hope this helps to clear things up. I should have done a better job explaining the differences the first chapter.**

 **Chapter 2**

Leonard Snart was standing in the middle of a small apartment. He paced back and forth in front of two police officers that were tied to chairs and silenced with tape on their mouths. One of the officers was an older man in his 50s while the other was in his late 20s. He carried his gun as he stopped in front of the older officer.

"I'm going to let you go. You are going to go back to your station. I want to know who the officers from Central City are. I want to know where they are. If you tip anyone off, I kill your partner. If you try anything, I kill your partner. Do you understand?"

"Go to hell," said the older officer. When Snart immediately pointed the cold gun at his partner he quickly changes his mind. "Wait, Wait! Don't do it. Why don't you just get the information yourself?"

"Walk into a police station with my face everywhere? No, you are going to do it because I think you care about what happens to your partner. Do as I say and you up both your chances of living."

"I'll do it. I'll do it just don't hurt him."

Barry spent his night racing around National City looking for signs of Snart. Tina was at her laptop helping Barry while Joe was busy with the local police. He was about ready to call it a night when Superman flew down. He was out on patrol when he saw Barry running around. The Kryptonian smiled since he now had his answer on whether the Flash existed or not. He decided to fly down and introduce himself since he had a feeling they would be seeing more of each other in the future.

"It's Superman. You're Superman. This is so awesome." Barry's expression quickly went from astonishment to excitement.

"Good evening, nice outfit. Who are you?"

"I uh, I'm the Flash. I have always wanted to meet you." Barry was thinking he must sound like a total fanboy, but he couldn't help himself. "I have so many questions I've wanted to ask you. What's it like being from another planet? Did you always know or did you find out later? Have you met any other…"

"Flash!" Superman was no stranger to being bombarded with questions, but he had a feeling they would be here all night answering his questions.

"Oh right, sorry about that." Barry was feeling embarrassed right now thinking he was making a fool of himself.

"It's okay. I assumer you're out here looking for Captain Cold."

"How did you know that?"

"Well he is the man of the hour at the moment."

"What's Kryptonite?" Knowing that now was the time to get serious Barry decided he would try and get some more answers.

"It's a dangerous substance to Kryptonians, that includes Supergirl and me. Being exposed to it can weaken us, make us vulnerable." Superman knew logically it was probably a bad idea to hand over this kind of information to a stranger, but after everything Kara had told him and his own encounter with Barry earlier he had a gut feeling that he could be trusted.

"We have to find Snart and that Kryptonite before that happens." Superman felt a little relief that his hunch was indeed correct.

"Are you suggesting we team up?" Superman tried to sound serious and authoritative.

"Oh uh, that is if you don't mind. Superman, sir."

Superman started laughing and that confused Barry. "Relax, I was only having a bit of fun. I wouldn't mind the help."

"Oh, you were joking." Barry let out a sigh of relief. "So yeah, okay then. How do you want to start?"

It was at the moment that Clark's super hearing kicked in and alerted him to a jumper on a bridge. "Sorry, I'll have to get back to you later. There's a jumper on a bridge and I need to go." He flew off after that leaving Barry to continue his search.

"What's impossible anymore," Barry couldn't help muttering to himself. Tina came in over his communicator at that moment.

"Barry, I think I have a lead on Snart."

"Really? Let's have it Tina."

"Two officers were reported as being missing all afternoon and only one came back. Joe told me that when the officer was questioned about his partner he started acting strangely. Barry the officer who returned was asking questions about some police from Central City."

"It's Snart," Barry said in realization. "He's targeting us. Did Joe say anything else?"

"No, I'm not a cop Barry he would only tell me so much."

"Okay, I'm going to talk to him." Barry sped off after that. He found Joe at the police station where he had been all afternoon.

"Barry, there you are. Listen, I just heard that Snart might be looking for us." Joe and Barry were walking of to a corner of an office now.

"Tina told me. Do you have any idea where this guy and his partner were last seen?"

"He wouldn't say were they were. He was just acting really suspicious when he was questioned about it. "

"Who is this officer, do you know?"

"His name was Meadows, Tim Meadows. Look Barry, I want you to stay with Tina at the apartment for the time being."

"Yeah, sure." Joe left after that since he needed to get back to work. Barry on the other hand decided to track down Meadows. He managed to convince an officer at the station to tell him that Meadows let it slip he and his partner were called to a domestic dispute at an apartment downtown. After getting the name of the apartment Barry sped off to search the building.

When he got there Barry as the Flash found Meadows lying on the floor and the other officer tied to a chair with Snart looking over them.

"Who are you?" Snart looked the man in the red suit up and down.

"I'm the Flash, nice to meet you. I'll be taking you to jail this evening."

"So you do exist. You're younger than I imagined." Snart had his cold gun aimed at the scarlet speedster now.

"Where is the rock Snart? What did you do with it?"

"In a minute it won't matter to you."

"Don't try it Snart. You know I'll just dodge it."

"But can he," Snart turned the cold gun on the officer tied to the chair. Barry went wide eyed in realization before acting. He sped over to the officer and knocked his chair over before being hit with the cold gun.

Barry rolled on the ground in agony at the freezing ice covering his body. Cold walked over and hit him over the head with his gun, knocking him out.

"I didn't expect to deal with you, but this will be the last time." Snart aimed the gun at Barry again before Supergirl made an entrance catching Cold's attention.

"Put the gun down Snart."

"And another one shows up. Too bad you won't be taking me today. You can chase after me or save the Scarlet Speedster over there, your choice."

That is when Kara looked over to see someone she never thought she would see again. Her eyes widened at seeing Barry Allen, the Flash lying on the ground covered in ice. She looked over at Snart who was already gone. Deciding that helping Barry was more important she freed the officer tied to a chair and instructed him to get his partner out of there. She then took Barry in her arms and flew away quickly.

It was some time later that Barry awoke in a strange place. He looked around and noticed who was in a room with large windows looking out into an office with many people. His mask was off and the top half of his suit was open as he lay on a bed with monitors beside him.

Supergirl soon walked in to surprisingly find him awake. "Barry," she said in excitement and relief at seeing he would be alright.

"What, what's going on? Where am I?"

"I found you unconscious in an apartment. You were hit with Captain Cold's gun so I brought you here."

"Supergirl? Where is here?" Barry's mind was running a million miles a minute with a need for answers. "Wait you said my name. How do you know who I am?"

"Well, here is the DEO. As for your other question, that is a little harder to explain."

It was then that Hank, Alex, Winn and Superman walked in. "Oh he looks so much like the other one. Guess the other worlds thing was real," said Winn.

After some explaining Barry was trying to process everything. They had explained to him about meeting the other Flash as well as what the DEO was. "So let me get this straight. You met another me from a parallel earth and that's how you knew who I am."

"Basically yeah," Kara said. "I didn't even think a Flash existed in this world, but I'll never forget meeting that other Barry."

"I'm still wondering why I haven't heard about this until now." Hank was not around when the other Barry was here so he never learned about it. Alex was feeling the same way, she figured that her sister would have at least told her.

"I know you're probably not happy about your identity being exposed like this, but I didn't know what else to do. I saw you covered in ice and I just acted."

"It's okay Supergirl," Barry assured her. "You saved my life so I can't be too mad."

"Kara," she said with a smile. "You can call me Kara."

Hank was clearly not happy about Kara giving out her real name so easily. Especially since he didn't know anything about Barry.

"I'm sorry I wasn't there," Superman said. "I said we'd work together on this. If I had been there you would have had backup."

"Don't worry about it. You said there was a jumper, they needed you more than me. How did that go by the way?"

"It was a trap. I think we found that Kryptonite that Snart stole."

"I'm sorry I wasn't there Kal. I was on my way when I heard Barry and Snart in that apartment…" Kara felt bad that she wasn't there to help her cousin. John Corbin now had a Kryptonite heart and was going by Metallo. When Superman showed up he was attacked and weakened, but he managed to deal with Corbin and get away for now.

"No Kara, I'm glad you weren't there. He could have hurt you too. We'll find a way to deal with Corbin, then go after him."


End file.
